<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <script>
        let obj = {
            name:'jack',
            age:21,
            hobbies:['唱歌','画画','运动'],
            games:{},
            memo:undefined,
            test:null
        }

        console.log(obj.hasOwnProperty('hobbies'));
        console.log(obj.hasOwnProperty('games'));
        console.log(obj.hasOwnProperty('memo'));
        console.log(obj.hasOwnProperty('test'));
        console.log(obj.hasOwnProperty('test2'));

        // true true true true false
    </script>
</body>
</html>
